TWI815714B - Device and method for collecting metal ions at the edge of silicon wafer - Google Patents

Abstract

The invention discloses a device and method for collecting metal ions at the edge of a silicon wafer. The device for collecting metal ions at the edge of a silicon wafer includes a T-shaped blocking element. The vertical connecting portion of the T-shaped blocking element is in contact with the edge of the silicon wafer. The connection part is provided with a droplet groove filled with scanning liquid to collect metal ions from the first part of the edge of the silicon chip by bringing the scanning liquid into contact with the first part of the edge of the silicon chip; a supporting element is used to support the silicon chip.

Description

Device and method for collecting metal ions at the edge of silicon wafer

The invention belongs to the technical field of silicon wafer detection, and particularly refers to a device and method for collecting metal ions at the edge of a silicon wafer.

Silicon wafers are obtained by using the Magnetic Field Czochralski Method (MCZ) to obtain single crystal silicon rods. The single crystal silicon rods are obtained through wire cutting, grinding, polishing, cleaning and other manufacturing procedures. During the processing of silicon wafers, there will be contamination by various metal impurities, which will lead to the failure of subsequent devices. Among them, light metals (such as Na (sodium), Mg (magnesium), Al (aluminum), K (potassium), Ca (calcium) ), etc.) will cause device breakdown and reduce the voltage. Heavy metals (such as Cr (chromium), Mn (manganese), Fe (iron), Ni (nickel), Cu (copper), Zn (zinc), etc.) will shorten the life of the device. reduce. As the raw material of the device, the metal ion content on the surface of the silicon wafer will directly affect the qualification rate of the device. Therefore, the metal ion content on the surface and edge of the silicon wafer needs to be detected and controlled below a certain specification to meet the subsequent process requirements.

However, during the process of collecting metal ions at the edge of the silicon wafer, both the metal ions in the upper and lower parts of the edge of the silicon wafer will be recovered. Therefore, currently the metal ion content in the upper or lower part of the edge of the silicon wafer can only be obtained through mathematical calculations. , this detection method results in low detection accuracy and large error in the detection of metal ion content at the edge of the silicon wafer.

In view of this, the present invention hopes to provide a device and method for collecting metal ions at the edge of a silicon wafer, which can improve the detection precision and accuracy of metal ion content at the edge of the silicon wafer, is simple to operate, and has high reliability.

The technical solution of the present invention is implemented as follows: First, the present invention provides a device for collecting metal ions at the edge of a silicon chip, which mainly includes: a T-shaped barrier element, a vertical connection portion of the T-shaped barrier element and a silicon The edges of the sheets are in contact with each other, and the transverse connection part is provided with a droplet groove filled with scanning fluid to collect the metal ions of the first part of the edge of the silicon wafer by bringing the scanning fluid into contact with the first part of the edge of the silicon wafer; the supporting element is used for Support silicon chip.

In a second aspect, the present invention provides a method for collecting metal ions at the edge of a silicon wafer. The collection method can be applied to the collection device of the first aspect. The steps include: moving the silicon wafer downward until the surface of the silicon wafer is connected to the opening of the droplet groove. contact; move the T-shaped barrier element so that the edge of the silicon sheet contacts the vertical connection portion of the T-shaped barrier element, and move the support element to support the silicon sheet; and connect the liquid droplet through the first part of the edge of the silicon sheet The scanning liquid in the tank contacts to collect the metal ions in the first part of the edge of the silicon wafer.

The invention provides a device and method for collecting metal ions at the edge of a silicon wafer; during the collection process, the first part of the edge of the silicon wafer is brought into contact with the scanning liquid in the droplet tank, and at the same time, it is connected vertically through a T-shaped barrier element The second part is in contact with the edge of the silicon chip to block the scanning liquid in the droplet groove from flowing to the second part of the edge of the silicon chip, thereby completing the collection operation of metal ions in the first part of the edge of the silicon chip. The collection device provided by the invention can collect only the metal ions in the first part or the second part of the edge of the silicon wafer. The operation is simple and the detection result error is small.

1:Collector

11: Syringe pump

12: Vacuum tube

13:Outer nozzle

14:Inner nozzle

15:Sealing plug

16:Valve

17: Vacuum pump

18: Edge support

3: Collection device for metal ions at the edge of silicon wafer

31:T-shaped barrier element

311: Vertical connection part

312: Horizontal connection part

3121: Droplet tank

32; Part One

33:Support element

34:Part 2

41: High pressure gas nozzle

A: The scanning fluid scans the surface of the silicon wafer

B: The scanning fluid scans at the edge of the silicon wafer

Dro: scanning fluid

W: silicon chip

S501~S503: step process

Figure 1 is a schematic structural diagram of a collector scanning the surface and edge of a silicon wafer in a conventional technical solution provided by an embodiment of the present invention; Figure 2 is a schematic diagram of collecting metal ions at the edge of a silicon wafer in a conventional technical solution provided by an embodiment of the present invention; Figure 3 is A schematic structural diagram of a device for collecting metal ions at the edge of a silicon wafer provided by an embodiment of the present invention; Figure 4 is a schematic structural diagram of a device for collecting metal ions at the edge of a silicon wafer provided by an embodiment of the present invention; Figure 5 is a schematic structural diagram of a device for collecting metal ions at the edge of a silicon wafer provided by an embodiment of the present invention. Schematic flow chart of the collection method of metal ions at the edge of silicon wafers.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

In related technologies, in order to test the content of ultra-trace metal ions, testing the metal ion content of silicon wafers requires the use of Vapor Phase Decomposition (VPD) and Inductively Coupled Plasma-Mass Spectrometry (ICP- MS) two types of equipment to perform quantitative ion analysis on the collected VPD liquid. The general steps include: S1. Transfer the silicon wafer to the VPD corrosion tank through the robot, and at the same time, pass the hydrofluoric acid (HF) solution into the VPD corrosion tank. Steam for 2 to 5 minutes to remove the oxide film on the surface of the silicon wafer, so that the metal ions in the film are free on the surface of the silicon wafer; generally speaking, a very thin silicon dioxide film will appear on the surface of the silicon wafer and the surface of the heated silicon wafer. Using hydrofluoric acid vapor as a cleaning agent, a silicon dioxide film with a thickness of about 10 angstroms is enough to be dissolved by 38% high-purity hydrofluoric acid within 5 minutes. At the same time, after the silicon wafer is cleaned with hydrofluoric acid, the outermost Si layer on the surface of the silicon wafer will (Silicon) almost has H-bonds (hydrogen bonds) as the terminal structure, and the surface is hydrophobic, which is conducive to the rolling of VPD droplets on the silicon wafer without Tail and residue are formed on the surface of the silicon wafer, thereby ensuring the integrity of the VPD droplet collection; S2. On the scanning platform of the ICP-MS equipment, absorb 1ml of VPD droplets through the nozzle of the surface metal collection system and place it on the surface of the silicon wafer or on the silicon wafer. Roll the edge of the wafer to collect the metal components on the surface of the silicon wafer; S3. Atomize the VPD droplets containing metal components and perform spectral analysis to test the metal content in the recovered liquid. Subtract each metal in the VPD droplets from the metal content in the recovered liquid. content to calculate the content of various metal ions on the surface of the silicon wafer.

Referring to Figure 1, it shows a schematic diagram of a collector 1 scanning the surface and edge of a silicon wafer W in the related art. As shown in Figure 1, the collector 1 mainly includes: a syringe pump 11, a vacuum tube 12, an outer nozzle 13, an inner nozzle 14, a sealing plug 15, a valve 16, a vacuum pump 17 and an edge support 18. Among them, the robot arm places the back side of the silicon wafer W with the surface oxide film removed on a stage with pores and adsorbs the back side of the silicon wafer W on the surface of the stage. The robot arm drives the bottom of the scanning outer nozzle 13 in the collector 1 and the The surface of the silicon wafer W is kept at a suitable distance; the syringe pump 11 injects the scanning liquid Dro into the cavity between the inner nozzle 14 and the outer nozzle 13, and the vacuum pump 17 extracts the air in the cavity between the inner nozzle 14 and the outer nozzle 13 to provide fixation. When the weight of the scanning liquid Dro is balanced with the degree of vacuum in the cavity between the inner nozzle 14 and the outer nozzle 13, the vacuum pump 17 stops pumping air. At this time, part of the scanning fluid Dro drops into the cavity between the inner and outer nozzles, and the other part is automatically suspended outside the cavity between the inner and outer nozzles, so as to be in contact with the surface of the silicon wafer W for scanning; finally, according to the set scanning route, Adjust the position of the scanning robot arm so that the scanning liquid Dro drops on the surface and edge of the silicon wafer W and other areas, and the scanning liquid Dro rolls on the surface and edge of the silicon wafer W to collect the metal components on the surface and edge of the silicon wafer W, as shown in Figure 1 As shown in A, the scanning fluid Dro scans on the surface of the silicon wafer, and as shown in B in Figure 1, the scanning fluid Dro scans on the edge of the silicon wafer.

However, as shown in Figure 1, when collecting metal ions in the upper part of the silicon wafer edge, the scanning fluid Dro will roll to the lower part of the silicon wafer edge. Specifically, as shown in Figure 2, when the scanning liquid Dro is dropped on the upper part of the edge of the silicon wafer, due to the structural characteristics of the silicon wafer edge and the tension of the scanning liquid Dro, When used, the scanning fluid Dro will flow to the lower part of the edge of the silicon wafer, so that the collected scanning fluid Dro contains not only the metal ions in the upper part of the silicon wafer edge, but also the metal ions in the lower part of the silicon wafer edge, affecting The detection precision and accuracy of metal ion content at the edge of silicon wafers are improved.

Based on the above description, embodiments of the present invention are expected to provide a device for collecting metal ions at the edge of the silicon wafer W, which can collect only the metal ions in the upper or lower part of the edge of the silicon wafer W during the entire detection process, so as to improve the performance of the silicon wafer W. Edge metal ion detection accuracy. Referring to Figure 3, it shows a silicon chip edge metal ion collection device 3 provided by an embodiment of the present invention. It mainly includes: a T-shaped barrier element 31, a vertical connecting portion 311 of the T-shaped barrier element 31 and The edges of the silicon wafer W are abutted, and the transverse connection portion 312 is provided with a droplet groove 3121 filled with scanning liquid Dro to collect the first portion 32 of the edge of the silicon wafer W by bringing the scanning liquid Dro into contact with the first portion 32 of the edge of the silicon wafer W. Metal ions; support element 33, the support element 33 is used to support the silicon wafer W.

It should be noted that in the embodiment of the present invention, the first part 32 of the edge of the silicon wafer W only represents the upper part or the lower part of the edge of the silicon wafer W, and is not limited to the edge part corresponding to the front side of the silicon wafer W or the back side of the silicon wafer W corresponding edge part.

For the acquisition device 3 shown in Figure 3, during the acquisition process, the first part 32 of the edge of the silicon chip W is brought into contact with the scanning liquid Dro in the droplet tank 3121 and relies on the tension of the scanning liquid Dro to cause the scanning liquid Dro to flow and The surface of the first part 32 of the edge of the silicon wafer W is filled, and at the same time, the vertical connecting portion 311 of the T-shaped blocking element 31 abuts the edge of the silicon wafer W to block the scanning liquid Dro in the droplet groove 3121 from flowing to the edge of the silicon wafer W. at the second part 34, thereby completing the collection operation of metal ions in the first part 32 of the edge of the silicon wafer. The collection device 3 provided by the embodiment of the present invention can collect only the metal ions in the first part 32 or the second part 34 of the edge of the silicon wafer W. The operation is simple and the detection result error is small.

For the collection device 3 shown in FIG. 3 , in some possible implementations, the part of the T-shaped barrier element 31 that is in contact with the silicon sheet W is covered with a flexible material. It can be understood that the parts of the T-shaped barrier element 31 that are in contact with the silicon sheet W are wrapped with flexible materials, which can prevent damage to the surface and edges of the silicon sheet W during the contact with the silicon sheet W.

For the above embodiments, in some examples, the flexible material is further configured to prevent the scanning liquid Dro in the first portion 32 of the edge of the silicon sheet W from overflowing to the second portion 34 of the edge of the silicon sheet W. It can be understood that in the embodiment of the present invention, not only the T-shaped blocking element is used to block the overflow of the scanning liquid Dro, but also the flexible material is used to create a sealing effect to isolate the overflowing of the scanning liquid Dro, so that the final collected scanning liquid Dro only contains The metal ions in the first part 32 of the edge of the silicon wafer W further improve the detection accuracy of the metal ions at the edge of the silicon wafer W.

For the collection device 3 shown in FIG. 3 , in some possible implementations, the portion of the support element 33 that is in contact with the silicon chip W is covered with a flexible material.

Specifically, in the embodiment of the present invention, the flexible material may be soluble polytetrafluoroethylene, polytetrafluoroethylene, etc.

18MΩ．cm，水質：電阻率>18.2MΩ．cm，TOC<5ppb。 For the collection device 3 shown in Figure 3, in some possible implementations, the components of the scanning fluid Dro are: hydrofluoric acid (HF) with a quality fraction of 0.264%~3%, and hydrofluoric acid (HF) with a quality fraction of 4%~11.42%. Hydrogen peroxide (H ₂ O ₂ ), the remainder is water (H ₂ O); among them, the quality concentration of hydrogen peroxide (H ₂ O ₂ ) is 35±1%, Japanese Tama Chemical AA-10 grade purity; hydrofluoric acid (HF) The quality concentration is 38%, Japanese Tama Chemical AA-10 grade purity; ultrapure water: resistivity

18MΩ. cm, water quality: resistivity>18.2MΩ. cm, TOC<5ppb.

For the collection device 3 shown in Figure 3, in some possible implementations, as shown in Figure 4, the collection device 3 also includes a high-pressure gas nozzle 41, and the high-pressure gas nozzle 41 is disposed toward the silicon. High-pressure gas is injected at the position where the edge of the silicon wafer W contacts the T-shaped barrier element 31 so that the scanning liquid Dro in the first part 32 of the edge of the silicon wafer W does not overflow to the second part 34 of the edge of the silicon wafer W. In order to further prevent the wall scanning liquid Dro from overflowing to the second part 34 and the upper surface of the edge of the silicon wafer W, during the specific implementation process, a T-shaped blocking element 31 is provided above the silicon wafer W in contact with the silicon wafer W. W contacts the high-pressure gas nozzle 41 in the direction of the T-shaped barrier element 31 .

For the above-mentioned embodiments, in some examples, the high-pressure gas nozzle 41 is also configured to inject the high-pressure gas along the second part 34 of the edge of the silicon wafer W to the position where the silicon wafer W contacts the T-shaped barrier element 31 .

For the above-mentioned embodiments, in some examples, the high-pressure gas injected by the high-pressure gas nozzle 41 is nitrogen. It can be understood that the high-pressure gas nozzle 41 injects inert gas to the contact position between the silicon wafer W and the T-shaped barrier element 31, which can not only further prevent the overflow of the scanning liquid Dro, but also the inert gas nitrogen will not affect the metal ion composition in the scanning liquid Dro. changes, which means it will not affect the test results.

Referring to Figure 5, it shows a method for collecting metal ions at the edge of a silicon wafer provided by an embodiment of the present invention. The collection method can be applied to the collection device 3 of the aforementioned technical solution. The steps include: S501. Move the silicon wafer downward until The surface of the silicon sheet is in contact with the opening of the droplet tank; S502, move the T-shaped barrier element so that the edge of the silicon sheet contacts the vertical connection portion of the T-shaped barrier element, and move the support element to support the silicon sheet ; S503. Collect the metal ions in the first part of the edge of the silicon wafer by contacting the first part of the edge of the silicon wafer with the scanning liquid in the droplet tank.

Understandably, after the collection of metal ions at the edge of the silicon wafer W is completed, the scanned scanning fluid is atomized and then subjected to spectral analysis to test the metal ion content in the recovered scanning fluid and the test before scanning. The content of metal ions in the scanning liquid; subtract the content of each metal ion in the scanning liquid before scanning from the content of each metal ion in the recovered scanning liquid, so that the content of various metal ions at the edge of the silicon wafer W can be calculated.

It should be noted that the technical solutions recorded in the embodiments of the present invention can be combined arbitrarily as long as there is no conflict.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field and having ordinary knowledge can easily think of changes or substitutions within the technical scope disclosed in the present invention. All are covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the patent application.

3: Collection device for metal ions at the edge of silicon wafer

31:T-shaped barrier element

311: Vertical connection part

312: Horizontal connection part

3121: Droplet tank

32:Part One

33:Support element

34:Part 2

Claims (9)

A device for collecting metal ions at the edge of a silicon wafer, which mainly includes: T-shaped blocking element, the vertical connecting portion of the T-shaped blocking element abuts the edge of the silicon wafer, and the lateral connecting portion is provided with a droplet groove filled with scanning fluid to pass the scanning fluid to the first part of the edge of the silicon wafer contact to collect metal ions from the first part of the edge of the silicon chip; A supporting element is used to support the silicon chip. The device for collecting metal ions at the edge of a silicon wafer as claimed in claim 1, wherein the portion of the barrier element in contact with the silicon wafer is covered with a flexible material. The device for collecting metal ions at the edge of a silicon wafer as described in claim 2, wherein the flexible material is further configured to prevent the scanning fluid from the first part of the edge of the silicon wafer from overflowing to the second part of the edge of the silicon wafer. The device for collecting metal ions at the edge of a silicon wafer according to claim 1, wherein the part of the support element that is in contact with the silicon wafer is covered with a flexible material. The device for collecting metal ions at the edge of a silicon wafer as described in claim 1, wherein the components of the scanning fluid are hydrofluoric acid (HF) with a mass fraction of 0.264% to 3%, and hydrogen peroxide with a mass fraction of 4% to 11.42% ( H ₂ O ₂ ), and the remainder is water (H ₂ O). The device for collecting metal ions at the edge of a silicon wafer according to claim 1, wherein the device further includes a high-pressure gas nozzle, and the high-pressure gas nozzle is arranged to abut against the T-shaped barrier element toward the edge of the silicon wafer. The high-pressure gas is injected at a position such that the scanning liquid in the first part of the edge of the silicon wafer does not overflow to the second part of the edge of the silicon wafer. The device for collecting metal ions at the edge of a silicon wafer according to claim 6, wherein the high-pressure gas nozzle is further configured to inject the high-pressure gas along the second part of the edge of the silicon wafer to the silicon wafer and the T-shaped spacer. The position where the blocking elements come into contact. The device for collecting metal ions at the edge of a silicon wafer according to claim 6, wherein the high-pressure gas injected by the high-pressure gas nozzle is nitrogen. A method for collecting metal ions at the edge of a silicon wafer, applied to the device for collecting metal ions at the edge of a silicon wafer as described in any one of claims 1 to 8, the steps include: Move the silicon chip down until the surface of the silicon chip is in contact with the opening of the droplet groove; Move the T-shaped barrier element so that the edge of the silicon sheet abuts the vertical connection portion of the T-shaped barrier element, and move the support element to support the silicon sheet; The metal ions in the first part of the silicon chip edge are collected by contacting the first part of the silicon chip edge with the scanning liquid in the droplet groove.